EVALUASI KINERJA DAS AIR BENGKULU DENGAN MENGGUNAKAN METODE HSS NAKAYASU DAN PROGRAM HEC-RAS VERSI 5.0.1 (Studi Kasus DAS Air Bengkulu)

Water inundation transfer from the upstream of the Air Bengkulu River resulted in floods inundating in Bengkulu City. Flooding resulted in a loss for scoitey. The watershed of air bengkulu river passes Karang Tinggi Subdistrict and Bangkahulu Subdistrict. By the condition of lan use Watershed of Air Bengkulu which used to forest turned into plantations and residences caused flooding in the rainy season. The purpose of this research was to obtain the peak discharge due to the intensity of rainfall in the Watershed of Air Bengkulu in analyzing the hydrology using Synthetic Unit Hydrograph (SUH) Nakayasu Method and to know whether the capacity of the Air Bengkulu River was still able to accommodate a Flood discharge with unsteady flow. For to know capacity of Air Bengkulu River, a hydrological alaysis using the Nakayasu methodh and hydraulic analysis using HEC-RAS 5.0.1. From the result of hydrology analysis, the peak discharge in Watershed of Air Bengkulu for a return period of 100 years by using SUH Nakayasu Method is 1111,3,18 m3/second. Data from the analysis simulated using HEC-RAS 5.0.1.from the simulation,condition in Watershed of Air Bengkulu for a return period of 2 years able to accommodate the discharge but for a return period of 5 years until 100 years unable to accommodate the discharge